Pole-piece.



Fiq

MTNSBSi-:s:

l PATSNTED AUG. s, 1905.

A. GHURGHWARI).

POLE PIECE,

APILIUATIOH TILE!) 00T. 35' N102.

` INVENTGR: allekander-hurchwrd. bw M nu un crus a. nur ummmumnrw. Le.

AUnitarian STATES.

PATENT ,OFFIGE. A

ALEXANDER CHURCHWARD, on NW YORK; NQY, SSIGNR T0 GEN anni,

ELEULRIC COMPANY, 'Av

CORPQRA'IIONOF NEW YORK.`

n ROLE-Piece.

To at?, whom it may concern."

Be it known that LALnxANDnn CHURCH- VWARD, a citizen of the United States, residing at New York, county of New York, State of New. York, have invented certain'new and useful Improvements in iolefPieces, of which the following is a specification. l

My invention relates to dynamo-electric machines, and has for its object the production of means whereby the sparking output.

of sncl1 machines may be controlled without adJnstment of the brushes about the commu- It has. been reeolgnized for some time that the sparking action of the brush was due -to thechange in the position of the neutral axis' caused by the variation of the loads upon iieid- 'poles having a non-uniform distribution of magnetic lines of force in their'working faces, The leading tips of the common 1Jole-pieces are worked up to the point of m ration under ordinary loads, whi e .the linx from the remainder of the pole-faces decreases in intensity from that point to the opposite tip, where it is practically zero, so that the mi' tip. When' increased load is thrown upon the center of the effective, area is near the iead polos, the flux from the unsaturated portion i .of the pole-face is increased so that the cent ter of effective area ismoved hackV farther away from the leading` tip. Attemptsy have been made heretofore to bring about a uniform distribution of themagnetic lines of,

-force in the working surfaces of field-poles; but eo far as I am aware these'attempts have not been satisfactory.

My invention consists in providing a fieldpole with means for 'concentrating the -liues of magnetic force near the working'face of. 'the pole, so that at ordinary loads the whole pole-piece near its working face will be worked .at the upper part of the curve of saturation, .und Awhen an overloadis thrown upon the machine the additional magnetic lines of force resulting therefrom will distribute themselves uniformly over the whole working face of the pole, and as a consequence the eife'ctive center of the total linx will not be changed. A rovide In carrying out my invention I transverse holes in thtl ends of the fie d-poles with their bases near the working'4 faces of the poles. I also contemplate using coppery end plates on the poles and connecting them by bars which shall pass through the holes in Specification of Letters Patent.. applicant and canteras, 19er. Beamtinnen,

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My invention will bereadily-understood npon'- reference tothe accompanying drawings, forming a part of the epeciii'cation and l Yshowing anembodirnent of my invention, in wi11ch Figure 1 is adiagrammatic view of adyuamo-electric machine 'with two field-poles in elevation and one in longitudinal section. Fig'.

2 is a bottom plan of a polepiece shown inP Fig. 1, and Fig. 3 is a longitudinal section of;

a modified form of pole-piece. A

this arrangement the linx :under ordinary loads is grad nelly 'concentrated from the ver#v tex ofthe triangular holes 3 until it reaches the plane'of their bases, where .it permeates the iron for a ver'y short distance at a comparatively hi' h degree of saturation.` 'After passing the p ape of their bases it is free' to spread outnagain and distribute itself in the metal between the bases of the holes and the working end of the pole. Care should be taken, however, that this metal so remaining should not b e suiiicient to allow'a .cross dow of the Eux toward the leading' tip ofthe pole.- As shown in Figs. 1 and 2, the pole-piece is provided with a prcjectin shoulder 4:, which serves to support the fiel spool 5. The end plates-6 'of the pole-piece are of copper or other good conducting material and are connected with each other and held in position by conducting-rods 7. which pass freely through Vthe holes 3. The arrangement shown in Fig.

3 is the saine except that the end plates ex- -tend the fulllength of kthe pole-piece, while in the first form the end plates cover only that part of the pole-piece visible beneath the inner end ofV the held-coils.

It is apparent that the shape of the transverse holes 3 need not necessarily be triangular, for' any shape or size ofV hole which will the pole-pieces inorderl to neutralize fcrossmake the concentration of thc magnetic lines I ol force greatest near the pole-face is adapted to carry ont my invention.

What I claim' as new, and desire to secure by Letters Patent of the United States, is-

1. 1n a dynamo-electric machine, a polepiece havingr a triangular slot formed in it, said slot being located near the face el the pole and drawn parallel to the axis of the ermature 0i" the machine, with one Hat side of the slot substantially parallel to and closely adjacent to the pole-piece.

2. A magnetic pole having a hole formed in it, said hole having one side parallel to the face of the pole, the erosseseetional area ot' the hole beyond said Side diminishing with the distance from the pole-face.

remos:

3. A magnetic pole having therein one er more triangular holes with one side parallel and in proximity to its working face.

4. A magnetic pole having therein triangular holes in proximity to its working face.

5. A magnetic pole having therein triangular holes with one side parallel with and in proximity to its working face.

6. A magnetic pole having triangular holes in proximity to its working face, and means for neutralizing cross-Curran ts.

In witness whereof 1 have hereunto set my hand this 22d day of October, 1902.-

ALEXANDER CHURCHVV ARD. Witnesses:

L. C. Fosa` C. D. Renn. 

